[Zope] Object ids in the select

If I have the code : <form action="setmember" method="post"> <select name="members" size="10" multiple> <dtml-in catalog> <option value="<dtml-var catalog.getobject(data_record_id_)>"> <dtml-var title> </option> </dtml-in> </select> <input type="submit" value="addmembers"> </form> How I can retrieve the object-ids in setmember. If setmember is a python method, what is passed to it? I have the which collect objects in its attribute as a list.